The Galileo Mission: Hard-Won But Successful

Sept. 17

By Lee Dye

— How about this for a fitting end to a science fiction movie? Our exhausted hero, having fought nearly impossible odds and won every time, is now so old that his memory is shot and his energy is gone, but he still poses some danger to the distant reaches of the solar system.

To remove that one last threat, in the dark of night, we'll vaporize him.

That's the fate that now awaits Galileo, a spacecraft that has risen from its own ashes more times in the last couple of decades than a cat has lives. But that won't happen this time. Several months ago the robotic curmudgeon expended its last bit of energy to set itself on a collision course with Jupiter.

So scientists and engineers at NASA's Jet Propulsion Laboratory in Southern California can now only do what they've learned to do so well in the past. They must wait. Nothing else needs to be done.

And finally, shortly after midnight Sunday, Galileo will plunge into the thick atmosphere of Jupiter at 30 miles per second, ripping itself to shreds before its last pieces of metal are vaporized, ending one of the truly remarkable adventures in the nascent history of space exploration.

Back to Where It Belongs

That's as it should be. It took Galileo so long to get there that Jupiter is where it should remain, along with whatever earthly microbes it carried into space. NASA decided to destroy the spacecraft rather than risk having any of those tiny critters wind up on Europa and thus taint any results from a planned search for life on that Jovian moon.

Many scientists believe the fractured fields of ice on Europa's surface cover a liquid ocean, thus offering us our best chance of finding some form of life elsewhere in the solar system.

Several hundred persons are expected to be on hand at JPL to witness the demise of their charge. They won't see anything, of course. The only proof that the epic mission to Jupiter is over will be silence, the weak radio aboard the spacecraft will have finally died.

But as is so often the case, not everybody who has played a key role in this story will be on hand to witness its conclusion. By the time Galileo reached Jupiter in 1995, four of the lead scientists and engineers at JPL, who had nurtured the spacecraft through political minefields and across technological chasms, had died. Others have died since, including a couple of dozen who were involved in the project through other institutions.

The mission took so long because at times fate seemed set against it.

Winging It

After many delays in launching the spacecraft, it was finally set to go in the mid-1980s when the Challenger exploded. In the aftermath of that tragedy, new regulations prohibited the use of the upper stage rockets that were to have carried Galileo from the space shuttle to Jupiter.

That left the folks at JPL with seemingly no way to launch Galileo, and it seemed for awhile that the mission was dead. Then they came up with a bold scheme. Galileo was launched from the shuttle in 1989, but in the wrong direction. Instead of heading out toward the outer planets, Galileo was headed for the sun.

It then used the gravity of Venus to slingshot itself back toward the Earth, and then on toward Jupiter.